1. Field of the Invention
The present invention relates to phased array antennas. More specifically, the present invention relates to digital phase shifters for high power radio frequency phased array antennas.
2. Description of the Related Art
An integral component of a wide-scan phased array antenna is a compact phase shifter. However, most state of the art phased array antennas for radar applications require phase shifters that switch in the sub-millisecond range.
In what is commonly referred to as a digital phase shifter, the length of the phase shifter is configurable from different lengths or sections of waveguides that can be selectively switched in or out. Typically, the various sections are lengths that are proportional to each other by factors of 2. For example, one length may be twice as long as another, second length. Yet a third length may be twice as long as the second length and so on. Thus, the various sections may be selectively switched in or out, thereby being combined to change the phase, incrementally. As the effective length of the overall phase shifter is changed, the phase changes proportionally.
There are few current applications for phased array antennas using slower phase shifters, i.e., with switching in the millisecond range. However, there are current directed energy system development programs that require a phased array antenna capable of radiating extremely high power. Further, directed energy systems do not require high speed phase shifters. Unfortunately, there are no compact phase shifters currently available for these applications.
Presently, only a ferrite phase shifter is available that is capable of handling these high power levels. However, this ferrite phase shifter is large, heavy, requires liquid cooling and is very expensive.
Thus, there is a need for a compact, high-power microwave phase shifter for use with phased array antennas in high power directed energy systems. There is also a need that such a high-power microwave phase shifter be lightweight and inexpensive.